Field of the Invention
This invention relates to hole plugs and, more particularly, to a fiberglass hole plug for sealing holes in electrical enclosures.
Description of Prior Art
Electrical enclosures of various sizes and shapes are used in many different applications. These enclosures are usually prefabricated with a plurality of prepositioned circular openings or holes for allowing electrical cables or wires to be installed through these openings for connection to a variety of electrical components secured within the enclosure. Depending on the type, number, and configuration of electrical components that are to be secured in the enclosure, an estimated number of openings are cut in the enclosure wall. If this estimated number of openings is high, a certain number of the openings will remain unused and exposed. Typically, it is advantageous to add additional openings for unexpected equipment or for future expansion. Electrical codes require that these unused openings be covered.
One method of covering these unused and exposed openings is the use of vinyl adhesive-backed dots which are placed over the openings. However, these vinyl adhesive-backed dots may not withstand corrosive or harsh outdoor environments where these electrical enclosures may be located. Other types of hole plugs, such as soft rubber plugs, may break down in some corrosive atmospheres because of their susceptibility to ultraviolet degradation and brittleness from extreme temperature variations. Typically, hole plugs that are able to withstand corrosive and extreme temperature variations are typically made of stainless steel, zinc plated carbon steel or painted carbon steel. However, the cost associated with these types of materials for use in the manufacture of hole plugs is expensive.
One such prior art hole plug that overcomes the above deficiencies is shown in FIGS. 1-4. FIG. 1 shows a prior art hole plug 10 made of fiberglass and manufactured by Stahlin Enclosures, Inc. Referring to FIGS. 1-4, the hole plug 10 includes a first section 12 and a second section 14, wherein the first section 12 includes a cover 16 having a first side 18 and a second side 20 and a threaded member 26 having a first end 28 and a second end 30. The second end 30 of the threaded member 26 is attached to the second side 20 of the cover 16 and axially extends in a direction away from the second side 20 of the cover 16. The first side 18 of the cover 16 can be dome-shaped. A planar surface having an annular groove 22 is defined on the second side 20 of the cover 16. A center cavity 32 defined in the threaded member 26 extends from the first end 28 to the second end 30 of the threaded member 26. The second section 14 of the hole plug 10 shown in FIG. 1 includes a fastener 36 such as a nut. Referring to FIG. 3, the fastener 36 includes an annular body 38 having a first end 40 and a second end 42. An internally threaded center passageway 44 is defined in the body 38 and includes internal grooves 46 for receiving the threaded member 26 of the first section 12. The fastener 36 also includes a flange 48 having a first surface 50 and second surface 52. The first surface 50 of the flange 48 is attached to the first end 40 of the body 38. The fastener also includes a pair of tabs 54 opposed to each other and integrally attached to the first surface 50 of the flange 48 and the body 38. Each tab 54 extends from the first end 40 to the second end 42 of the body and in a radial direction away from the center passageway 44.
FIG. 4 shows the prior art hole plug 10 installed in a panel wall 62 of an enclosure having an opening 68 defined therein. The threaded member 26 extends through the opening 68 and the fastener 36 threadably engages the threaded member 26, whereby rotation of the fastener 36 adjusts a longitudinal distance between the fastener 36 and the second end 30 of the threaded member 26 until the second surface 52 of the flange 48 is secured against a second surface 66 of the panel wall 62. When the fastener 36 is tightened, the second side 20 of the cover 16 engages the first surface 64 of the panel wall 62, thereby forming a seal.
However, the problem with the prior art hole plug 10 is that a specific amount of torque is oftentimes required to achieve a proper seal. To accomplish this, a custom made torque wrench has to be fabricated and used to achieve the required torque. Because hole plugs are generally installed in an enclosure that is already set up or positioned in the desired location, these custom torque wrenches are typically lost or not available. Oftentimes, these hole plugs are tightened with a user's hand during installation. Because of inconsistency in strength from one person to another, the location of the hole plug, such as being in a hard to reach place and the fatigue of a user's hand, the appropriate torque is difficult to achieve each and every time, particularly when hand tightened. Such inconsistent torque may lead to an improper seal thus drastically reducing the hole plug's sealing capabilities. This is particularly important when a large number of hole plugs are used for one enclosure, wherein even one seal failure of a hole plug can cause foreign substances such as water and/or dust to seep through thus damaging the entire contents within the enclosure.
It is, therefore, desirable to overcome the above deficiencies by providing a hole plug that can be consistently sealed properly to an enclosure when hand tightened such that the hole plug's sealing capability is drastically increased.